What is the chemical symbol for water?

What is the hardest natural substance on Earth?

Which gas is most abundant in Earth’s atmosphere?

Which metal is liquid at room temperature?

Which gas is commonly used to inflate balloons?

Which gas is commonly known as laughing gas?

Which element is necessary for strong bones and teeth?

Which blood cells help in clotting?

Which type of mirror is used in car side mirrors?

Which pigment gives plants their green color?